Hair piece design



FIG. 1 is a front view of the ornamental hair piece design;

FIG. 2 is a rear view thereof;

FIG. 3 is a left side view thereof; and,

FIG. 4 is a top view thereof.

The broken lines to the netting in FIG. 1 are not part of the claimed design. 

The ornamental design for a hair piece design, as shown and described. 